1. Field of the Invention
The present invention relates to a laminate of elastomers.
2. Description of the Related Art
Acrylic elastomers and vulcanized products thereof, which are superior in physical properties such as heat-aging resistance, oil resistance, mechanical properties and compression set characteristics, have been used widely, for example, as the materials for hose parts, sealing parts and antivibration rubber parts in automobile engine rooms.
Under recent regulations tightening exhaust gas, mandating increases in engine output and others, there is a demand for parts with higher heat-aging resistance.
To solve the problems above and to improve the reliability of rubber parts, it is conceivable to use fluorine elastomers that are higher in durability than acrylic elastomers. However, fluorine elastomers, which are lower in low-temperature resistance and also expensive, are not ideal materials particularly for auto parts that demand cost-effectiveness and reliability simultaneously.
For example, Patent Documents 1 to 4 below disclose laminates of a fluorine elastomer layer and an acrylic elastomer layer. It is possible to raise the durability of a conventional material substantially by laminating a fluorine elastomer on the region thereof where there is truly a problem in durability.
An important requirement demanded when a laminate is produced from fluorine and acrylic elastomers includes bonding strength between these layers. Because low bonding strength between them impairs reliability of the laminate, it is extremely important to increase the bonding strength between them to obtain an inexpensive laminate higher in durability.
For that reason, the surface of the fluorine elastomer is subjected, for example, to surface-treatment with a metal sodium solution (see, for example, Patent Document 1), discharge treatment (see, for example, Patent Document 2), or plasma treatment (see, for example, Patent Document 3) for improvement of the bonding strength with an elastomer molded in a layer shape. It is also known that it is possible by using a particular kind of fluorine elastomer to improve the bonding strength between a fluorine elastomer layer and a non-fluorine elastomer layer (see, for example, Patent Document 4).